Nutrient composition for exercise

ABSTRACT

A method of maintaining raised blood glucose levels in a mammal during excise, preventing or delaying the onset of hypoglycemia during excise. The method includes step of orally administering to the mammal a nutrient composition containing a carbohydrate source and at least 9% by weight beta-glucan.

This application is a 371 of PCT/EP97/00448, filed Jan. 27, 1997, whichclaims the foreign priority of EP 96200301.8, filed Feb. 9, 1996.

This invention relates to a nutrient composition which may be used tomaintain raised blood glucose levels for extended periods duringexercise and which reduces acid reflux symptoms. The invention alsorelates to methods of maintaining raised blood glucose levels forextended periods, methods for the prevention of hypoglycaemia, methodsfor increasing exercise performance and methods for reducing acid refluxsymptoms; especially in athletes.

Humans, during exercise, obtain the energy necessary for the exercisepredominantly from two sources; carbohydrates and lipids. However, therate at which energy is supplied to muscles through carbohydrates is 3to 4 times higher than for lipids: making carbohydrates an extremelyimportant source of energy for athletes.

During exercise, carbohydrates are supplied to the muscles either in theform of blood glucose or muscle glycogen. The availability ofcarbohydrates from these sources is very dependent upon exerciseintensity and duration. However during exercise of high intensity,muscle glycogen is consumed first and rapidly. This requires thatsufficient blood glucose be present as an energy source for continuedperformance. For this reason, athletes often ingest large quantities ofcarbohydrates before and during exercise.

Unfortunately, the ingestion of carbohydrates results in a blood glucosepeak shortly after ingestion; along with a concomitant peak in bloodinsulin. This is then followed by an equally rapid drop in blood glucoselevels. If the drop is sufficiently large, reactive hypoglycaemia andits associated unpleasant symptoms will result. Further, fatigue mayrapidly set in; greatly reducing exercise performance.

Further, many athletes who subject themselves to severe training sufferfrom gastro-oesophageal acid reflux; a condition which has extremelyunpleasant symptoms. The condition is believed to arise from delayedgastric emptying and excessive oesophageal pressure. In severe cases,symptoms include vomiting of blood.

It is therefore an object of this invention to provide an energy sourcewhich is capable of maintaining raised blood glucose levels for extendedperiods. It is a further object of this invention to provide an energysource which prevents or reduces the occurrence of gastro-oesophagealacid reflux.

Accordingly, in one aspect, this invention provides a method ofmaintaining raised blood glucose levels in a mammal during exercise, themethod comprising orally administering to the mammal a nutrientcomposition containing carbohydrate and soluble fibre.

In another aspect, this invention provides a method of preventing ordelaying the onset of hypoglycaemia during exercise, the methodcomprising orally administering to the mammal a nutrient compositioncontaining carbohydrate and soluble fibre.

In a further aspect, this invention provides a method of preventing orreducing acid reflux symptoms in a mammal, the method comprising orallyadministering to the mammal a nutrient composition containingcarbohydrate and soluble fibre.

In a yet further aspect, this invention provides the use of carbohydrateand soluble fibre in the preparation of an orally administrable nutrientcomposition for the maintenance of raised blood glucose levels in amammal during exercise, the prevention or delay of the onset ofhypoglycaemia in a mammal during exercise, or the prevention orreduction of acid reflux symptoms in a mammal.

The invention also provides a nutrient composition for the maintenanceof raised blood glucose levels in a mammal during exercise, theprevention or delay of the onset of hypoglycaemia in a mammal duringexercise, or the prevention or reduction of acid reflux symptoms in amammal, the nutrient composition comprising carbohydrate and solublefibre.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates, graphically, blood glucose levels versus time forthree breakfasts as well as at rest, pursuant to Example 2.

Surprisingly, it is found that administering a nutrient compositionwhich contains carbohydrate and an effective amount of soluble fibres toa mammal results in a relatively small increase in the blood glucose ofthe mammal and that this raised level of blood glucose is maintained forextended periods during exercise. This prevents or delays the onset ofhypoglycaemia during exercise. Also, the onset of fatigue is delayedwhich enables an increase in performance. If a nutrient compositioncontaining an equivalent amount of carbohydrate, but without solublefibre, is administered, the blood glucose levels of the mammal rapidlyincrease to a peak and then rapidly decrease upon onset of exercise towell below base blood glucose levels. In these circumstances,hypoglycaemia may rapidly result along with fatigue and reducedperformance.

It is also surprisingly found that orally administering a nutrientcomposition which contains carbohydrate and an effective amount ofsoluble fibre prevents or delays the onset of the symptoms of acidreflux.

Preferably the nutrient composition contains at least 2% by weightsoluble fibre: more preferably at least 5% by weight soluble fibre; forexample about 8 to about 15% by weight soluble fibre.

The nutrient composition preferably contains up to about 60% by weightof carbohydrate; more preferably about 40% to about 55% by weight of thecarbohydrate source; for example about 45% to about 55% by weight.

The nutrient composition may also include fats; preferably up to about20% by weight of fats; more preferably about 8 to about 18% by weightfats. For example, the nutrient composition may include about 10% toabout 15% by weight fats.

The nutrient composition preferably has up to about 20% by weight ofprotein; more preferably about 8 to about 18% by weight protein. Forexample, the nutrient composition may include about 10% to about 16% byweight protein.

Preferably the nutrient composition includes a fibre rich cereal whichprovides carbohydrate and the soluble fibre. Preferably the fibre richcereal contains at least about 10% by weight of soluble fibre and atleast about 25% by weight of total fibre. More preferably the fibre richcereal contains at least about 14% by weight soluble fibre and at leastabout 30% by weight of total fibre. The fibre rich cereal is preferablyan oat bran concentrate or a barley flour; more preferably a de-fattedoat bran or barley flour.

The fibre rich cereal is preferably provided in the form of an extrusioncooked cereal. In this form, the fibre rich cereal has the advantagethat it is in a ready to eat form and has acceptable taste and texture.Preferably the nutrient composition is in the form of a ready to eatsnack bar.

The nutrient composition is preferably administered from about 2 hoursto about 15 minutes prior to commencing exercise. The nutrientcomposition may also be conveniently administered during exercise orduring rest periods in exercise of longer duration.

The amount of nutrient composition administered is preferably sufficientto provide about 0.03 g to about 0.3 g per kg body weight of solublefibre; more preferably about 0.05 g to about 0.2 g per kg body weight ofsoluble fibre. For example, the amount of soluble fibre administered maybe about 0.07 g about 0.15 g per kg of body weight. The amount ofcarbohydrate administered is preferably sufficient to meet energy needs,for example about 0.3 g to about 1.5 g per kg body weight. Morepreferably about 0.8 g to about 1.2 g per kg body weight of carbohydrateare administered.

Embodiments of the invention are now described, by way of example only,with reference to the drawing which is a graph of blood glucose levelsin athletes plotted against time after consumption of different mealshaving the same carbohydrate content. Breakfast A is a maltodextrinsolution. Breakfast B is a mixture of maltodextrin solution and snackbars containing soluble fibre, and Breakfast C is made up of snack barscontaining soluble fibre. Certain athletes remain at rest and are fedBreakfast C.

To produce the nutrient composition, a soluble fibre source is required.Any suitable source of soluble fibre may be used. However, the source ofsoluble fibre is conveniently selected to be compatible with the form ofthe nutrient composition desired. For example, if the nutrientcomposition is to be in the form a breakfast cereal, a snack bar, acookie, a biscuit, a cracker, a bread or bread-like product, etc, thesoluble fibre is conveniently provided in the form of a fibre richcereal or a fibre rich bean concentrate.

For convenient, ready-to-eat foods such as snack bars, the soluble fibreis best provided in the form of a fibre rich cereal. For simplicity, theinvention will be described in detail in relation to the use of fibrerich cereals as a soluble fibre source. However, it will be appreciatedthat the invention is not limited to the use of fibre rich cereals. Forother sources of soluble fibre, procedures known in the art may be usedto produce the nutrient compositions.

For best results when using a fibre rich cereal, the fibre-rich cerealhas a total fibre content of at least 25% by weight and a soluble fibrecontent (the soluble fibre being predominantly β-glucan) of at least 10%by weight. The fibre rich cereal may be any suitable cereal; for exampleoat or barley. Particularly suitable is oat bran concentrate but barleyflours (for example obtained from Conagra Inc. of Omaha, Nebr., USA) arealso suitable. Most preferred are de-fatted oat bran concentrates.

In this specification, a “de-fatted oat bran concentrate” means an oatbran fraction which has a soluble fibre content of above about 10% byweight and which has been subjected to solvent extraction to remove, atleast partially, oils and fats from the fraction. Ordinarily, oat branconcentrates have a fat or oil content of greater than about 10% byweight. De-fatted oat bran concentrates have an oil or fat content ofless than about 7% by weight: more usually about 4% to about 6% byweight. De-fatted oat bran concentrates offer the advantage of betterstability of the nutrient composition, easier processing, and improvedtexture and organoleptic properties of the nutrient composition.

De-fatted oat bran concentrates of this type are commercially available;for example suitable oat bran concentrates may be purchased from SwedishProtein AB. Väröbacka, Sweden. Alternatively the oat bran concentratemay be prepared by grinding dry oat grains and then carefully screeningthe fibre material from the starchy components of the oat grains. Thefibre rich material may then be subjected to solvent extractiontechniques to remove oils and fats from the material. A suitableprocedure for the extraction of oils and fats is disclosed in Britishpatent 1,526,553; the disclosure of which is incorporated by reference.The solvent extraction step may also be carried out prior to screeningif desired. This screening and extraction procedure would be suitablefor producing oat bran concentrates with fibre contents at the lower endof the range; for example an oat bran concentrate having a maximumsoluble fibre content of about 15% by weight.

As an alternative, the process described in U.S. Pat. No. 5,106,640 (thedisclosure of which is incorporated by reference) may be adapted toproduce the de-fatted oat bran concentrate. In this process, oat grainsare rapidly ground in slurry form at a temperature of 0 to 15° C. Theslurry is then homogenised and then screened to separate off a fibrerich fraction. The fibre rich fraction may then be subjected toextraction to remove oils and fats. Using this technique, oat branconcentrates having a soluble fibre content of up to about 40% by weightmay be prepared. Although oat bran concentrates having very high solublefibre contents may be used to produce the nutrient composition, it ispreferred if the soluble fibre content is less than about 20% by weight.

To produce the nutrient composition, a dry mix containing the fibre richcereal is formed. The dry mix will comprise at least 50% by weight ofthe fibre rich cereal; the exact amount depending upon the desired formand desired properties of the nutrient composition.

If it is desired to produce an expanded nutrient composition, the drymix will usually also contain a starchy, farinaceous ingredient or astarch, or both. Any suitable starchy farinaceous ingredient may beused. Suitable examples are wheat flour, rice flour, corn flour, barleyflour, oat flour, and rye flour. Also mixtures of these flours may beused. The flours may be whole flours or may be flours which have hadfractions removed; for example the germ fraction or husk fraction may beremoved. Rice flour and wheat flour are particularly suitable; eitheralone or in combination. For example, up to 40% by weight of thestarchy, farinaceous ingredient or starch may be used although adequateexpansion may be obtained with lower amounts of the starchy, farinaceousingredient or starch.

The amount of the starchy, farinaceous ingredient or starch that is usedis selected to provide the desired properties in the nutrientcomposition. However it is best that the soluble fibre content of thenutrient composition is above about 5%. If it is desired to provide ahighly expanded product, greater amounts of the starchy, farinaceousingredient or starch will be needed. In this case, the soluble fibrecontent of the nutrient composition may be maintained above about 5% byweight by using an oat bran concentrate with a high soluble fibrecontent. However, for a oat bran concentrate which has a soluble fibrecontent in the range of about 15 to about 20% by weight, the starchy,farinaceous ingredient or starch conveniently comprises from about 10%to about 30% by weight of the dry mix.

If it is desired to produce a flaked nutrient composition, it is notnecessary to use a starchy, farinaceous ingredient or a starch in thedry mix since it is possible to flake an unexpanded product. In anyevent however, subjecting a dry mix which comprises almost exclusivelythe oat bran concentrate will result in some expansion. Extensivelyexpanded products may also be flaked.

The dry mix may also include minor amounts, for example less than 5% byweight in total, of flavouring agents, colouring agents, salts,antioxidants, vitamins, minerals, protein sources, malts, and the like.Suitable protein sources are milk powders, whey powders, wheat glutensetc. If desired, further sources of insoluble fibre may also beincluded; for example wheat bran, corn bran, rice bran, rye bran and thelike.

The various ingredients of the dry mix are then mixed to provide ahomogeneous mix and are then fed to a suitable cooker to increase thepalatability of the fibre rich cereal; for example an extruder-cooker.Any suitable extrusion cooker may be used; single crew or twin screw.Suitable extrusion cookers may be commercially obtained; for example theWenger and Clextral extrusion cookers which are widely available andwell known in the art. Twin screw extruders which have co-rotating andinter-penetrating screws are particularly suitable.

Water is also fed into the extruder-cooker, usually into the second zoneof the extruder-cooker, to enable gelatinisation of starch components.The water may be at a temperature of about 20° C. to about 60° C. Theamount of water used may be selected as desired but preferably makes upless than about 25% by weight of the total weight of the water and dryingredients. If too much water is used, it is found that the end productbecomes very hard and dense. Although this may not be too serious if theend product is to be flaked, it is best avoided if the end product is toused in expanded form. For expanded nutrient compositions, the amount ofadded water used is preferably less than 15% by weight of the totalweight of the water and dry ingredients; for example about 10% byweight. Steam may also be used in place of water.

If desired, a very small amount of an edible oil may be fed into theextruder-cooker to facilitate the extrusion process or as carriers foroil soluble additives. Any suitable oil may be used; for examplevegetable oils such as sunflower oil, safflower oil, corn oil, and thelike. If oils are used, oils which are high in mono-unsaturates areparticularly preferred. Hydrogenated oils or fats are also preferred.The amount of oil used is preferably kept below about 1% by weight ofthe mixture of oil, dry mix and water.

The rotational speed of the screw or screws is preferably kept belowabout 500 rpm. Above about 500 rpm, it is found that the soluble fibresare degraded due to the high shear and the end product produces lowerviscosities in the stomach and small intestine. Rotational speeds in therange of about 200 rpm to about 450 rpm are suitable; particularlyrotational speeds in the range of 250 to 350 rpm.

The pressure in the shear and compression zones of the extruder-cookeris preferably kept below about 200 bars; for example a pressure in therange of about 100 to about 180 bars would be suitable. Particularlyadvantageous are pressures in the range of about 120 bar to about 140bar.

The maximum product temperature in the extruder is preferably kept belowabout 200° C.; for example in the range of about 80° C. to about 200° C.Particularly preferred are maximum product temperatures in the range ofabout 120° C. to about 190° C.; for example about 150° C. to about 180°C.

Upon leaving the extruder-cooker, the nutrient composition isconveniently cut into small pieces using rotating blades at the exit.Depending upon the conditions in the extruder-cooker, the nutrientcomposition expands to a greater or lesser extent. The nutrientcomposition intended to be flaked may, if desired, undergo much lessexpansion. Of course, it is possible to flake a highly expanded productbut there is no advantage in doing this.

If a flaked product is to be produced, the nutrient composition may thenbe transferred to a flaking apparatus. Suitable apparatus are well knownand widely used in the cereal industry and may be purchased from, forexample, Buhler AG in Switzerland. If desired, the nutrient compositionmay be partially dried before flaking.

The expanded nutrient composition or the flaked nutrient composition isthen dried to a moisture content below about 5% by weight. This isconveniently carried out in a hot air drier as is conventional. Moisturecontents of about 1% to about 3% by weight are preferred. The expandednutrient compositions produced in this way have a crispy, pleasanttexture and good organoleptic properties. The flaked nutrientcompositions also have good texture and organoleptic properties but areless crispy. The nutrient compositions have a pleasant taste of toastedcereal. The density of the nutrient compositions is conveniently lessthan about 300 g/l.

The nutrient composition may then be further processed as desired. Forexample, if the nutrient composition is to be used as a breakfastcereal, it may be sprayed with a syrup which contains sugars (such asfructose or glucose) or other sweeteners, colouring agents, orflavouring agents, and the like, and then dried. Then, if desired, driedfruit, nuts, other cereals, dried milk produce (such as dried yoghurtetc) may be dried mixed with or agglomerated with the coated nutrientcomposition.

Alternatively the nutrient composition may be formulated into aconvenience food such as a snack bar, a cookie, a biscuit, a cracker, amuffin and the like. Again the nutrient composition may be mixed withnuts, dried fruit, sugars or other sweeteners, colouring agents, orflavouring agents, and the like. To produce a snack bar, a suitablebinder, for example arabic gum or gelatine, may then be added. An agentwhich reduces breakability of the bar may also be included; for examplehydrolysed wheat. If desired, the bar may be coated with a suitablecoating; for example chocolate. Processes for manufacturing snack barsare well known and are described in the art; see for example U.S. Pat.No. 4,871,557.

The nutrient composition, when eaten, results in a smaller increase inblood glucose levels than other food compositions which contain anequivalent amount of carbohydrates but no soluble fibre. However, theraised blood glucose levels induced by the nutrient composition remainsubstantially constant over extended periods in comparison. Inparticular, little noticeable decrease in blood glucose levels occursupon onset of exercise. Consequently the onset of hypoglycaemia may beprevented or delayed for significant periods of time. Further the onsetof fatigue may be delayed: increasing exercise performance. Further thesymptoms associated with acid reflux are prevented or reduced.

The amount of the nutrient composition to be administered will varydepending upon the age, health and fitness of the individual, the bodyweight of the individual, the amount of carbohydrate and soluble fibrein the nutrient composition, the duration of the exercise, and the like.In any event, the correct amount for any individual may be rapidlydetermined by the individual or a medical practitioner. However, forexercise of duration up to about 1 to 2 hours, an amount of nutrientcomposition sufficient to supply a dose of about 0.03 g to about 0.3 gper kg body weight of soluble fibre is usually adequate. More preferablyabout 0.05 g to about 0.2 g per kg body weight of soluble fibre isadministered; for example, the amount administered may be about 0.07 gabout 0.15 g per kg of body weight.

The amount of carbohydrate administered is sufficient to meet the energyneeds of the user, for example a dose of about 0.3 g to about 1.5 g perkg body weight of carbohydrate for exercise of duration up to about 1 to2 hours would be adequate for most purposes. A dose of about 0.8 g toabout 1.2 g per kg body weight of carbohydrate is preferred.

The nutrient composition may be taken in single or multiple doses priorto commencing exercise; for example about 2 hours to about 15 minutesprior to commencing exercise. This is particularly suitable for exerciseof shorter duration; for example less than about 2 hours. Alternatively,the nutrient composition may be taken in multiple doses prior to andduring exercise. For example, if the individual is exercising overextended periods (for example, more then 10 hours), the nutrientcomposition may be taken prior to commencing exercise, during restperiods (if any) and during exercise if the individual is comfortablewith consuming food during exercise.

EXAMPLE 1

A dry mixture of about 82.4% de-fatted oat bran concentrate, about 15.6%wheat flour, about 2% powdered malt extract, and minor amounts of saltsand colouring agents is prepared. The oat bran concentrate is obtainedfrom Swedish Protein AB, Väröbacka. Sweden and contains about 35% totaldietary fibre and about 17% soluble fibre.

The dry mixture and water are fed into an extrusion cooker in a massratio of dry ingredients to water of about 4:1. The temperature at theexit of the extrusion cooker is about 122° C. The pressure in theextrusion cooker reaches about 126 bar. The product leaving the extruderorifices is cut into pieces of length of about 2 to 3 mm.

The pieces are then flaked in a flaking apparatus (obtained from BuhlerAG, Switzerland) and dried to a moisture content of about 2.3% using airat about 120° C. The dried flaked food product has a crispy, pleasanttexture, a dietary fibre content of about 29% and a soluble fibrecontent of about 14%. The product has a good mouthfeel.

A mixture of wheat flour and rice flour in roughly equal amounts issubjected to extrusion cooking to produced crisp, expanded balls. Thesecrisp balls are then mixed with the flaked food product in a mass ratioof crisp balls to flaked food product of about 1:8. Dried raisins areadded to the mixture in a mass ratio of raisins to flaked food productof about 1:2.8. A fructose syrup is prepared from fructose, arabic gumand water and is combined with the crisp balls, the flakes and theraisins. The mixture is formed into bars, cooled and cut into 20 gportions, all in a conventional manner. The bars are then given achocolate coating to provide individual bars of about 24 g.

The bars have a β-glucan content of about 10% by weight, a proteincontent of about 11% by weight, a total fibre content of about 20% byweight, a fat content of about 10% by weight, and a carbohydrate contentof about 50% by weight. The bars have good taste, texture and mouthfeel.

EXAMPLE 2

Three groups of twelve duathletes, who are regularly competing, areselected for the test. Each member of each group is fed a breakfastcontaining about 70 g of carbohydrate in the morning; no other foodbeing taken. The breakfast for the first group comprises a maltodextrinsolution (breakfast A). The breakfast for the second group comprises 3.8bars as described in example 1 and a maltodextrin solution to raise thecarbohydrates to 70 g (breakfast B). Two thirds of the carbohydrates inbreakfast B come from the bars. The breakfast for the third groupcomprises 5.7 bars as described in example 1 (breakfast C). Each memberconsumes the same amount of water (4.2 ml/kg).

About 30 minutes after eating the bars, all the athletes who hadbreakfasts A and B begin to exercise at a sustained pace for 2 hours.Half the athletes who had breakfast C also begin to exercise at asustained pace for 2 hours. In all cases, the exercise intensity, whichis measured at about 51 ml O₂/min per kg of body weight, is about 14 to15 times the basal rate. The other half of the athletes who hadbreakfast C are allowed to rest as a control.

Blood samples are taken prior to the breakfast and at about 15 minutes,about 30 minutes, about 45 minutes, about 60 minutes, about 90 minutes,about 130 minutes and about 150 minutes after the breakfast. In eachcase the blood glucose level is determined. The results are presented inFIG. 1.

The athletes who consumed breakfasts A and B experience a sharp increasein blood glucose levels at about 15 minutes after the breakfast. This isthen followed by a sharp drop in blood glucose levels about 15 to 20minutes into the exercise. In some cases, the blood glucose levels arelower than 2.5 mmol/l; a threshold often used as indicative of clinicalhypoglycaemia. The athletes who consumed breakfast C experience a smallincrease in blood glucose levels and a small decrease in blood glucoselevels during exercise. The blood glucose levels most closely resemblethose of the athletes who are at rest and remain relatively constant andraised.

The athletes are questioned on symptoms of gastrointestinal disturbancesbut little in the way of adverse symptoms are reported.

EXAMPLE 3

Various types of bar are produced substantially according to theprocedure of Example 1. Type 1 contains dried apricots and has achocolate coating; Type 2 contains hazel nuts and dried apricots and hasa chocolate coating; Type 3 contains dried apple pieces and has achocolate coating; Type 4 contains hazel nuts and dried apple pieces andhas a chocolate coating; Type 5 contains raisins and hazel nuts and hasa chocolate coating, and Type 6 is the bar of example 1. For all Types,soluble fibre content is about 9% to about 11% by weight, total fibrecontent is about 19% to about 21% by weight, carbohydrate content isabout 40% to about 49% by weight, protein content is about 13% to about15.5% by weight, and fat content is about 11% to about 17% by weight.

A long distance swimmer is required to swim for 7 days in theMediterranean. Each day, the swimmer eats breakfast at about 7 amcontaining about 900 kcal of energy of which about 580 comes fromcarbohydrates. The breakfast contains no soluble fibre. The swimmer thenbegins swimming and continues until 8 pm. During the day, the swimmeringests a snack of 3 bars of Types 1 to 6 and a drink containing 240kcal of sugar at 11 am. 1.30 pm and about 6 pm. Also the swimmer takes ameal at about 3 pm containing about 480 kcal of energy of which about280 comes from carbohydrates. The meal contains no soluble fibre. Bloodglucose levels are taken at each hour during the day.

After the breakfast and the meal, blood glucose levels increase sharplyand then drop equally sharply. The swimmer experiences painful acidreflux symptoms shortly after consuming the breakfast. Blood glucoselevels increase slightly or remain reasonably constant after consumingeach snack. No sharp decrease in blood glucose levels followingconsumption of the snack is determined. All acid reflux symptomsterminate upon consumption of the first snack at 11 am.

EXAMPLE 4

The Type 1 bar of example 3 is used. The bar has a soluble fibre contentof about 10% by weight, a total fibre content of about 20% by weight, acarbohydrate content of about 46% by weight, a protein content of about14% by weight, and a fat content of about 11% by weight.

Eight competitive cross-country skiers take part in the test. Each skieris fed a standard breakfast of about 830 kcal and then, 3 hours later,three bars of Type 1 making up about 210 kcal in energy. About 30minutes after consuming the bars, the skiers are each required to ski a2 km circular course 8 times. Cardiac frequency is measured and bloodsamples are taken at 180 and 30 minutes prior to commencing skiing, uponcommencing skiing and 60, 90 and 120 minutes after commencing skiing.Blood glucose levels are determined from the blood samples. The time foreach skier to complete 8 circuits is determined.

The test is repeated twice; in one repeat the bars are substituted by acommercial muesli bar in an amount sufficient to provide about 210 kcalin energy. In the other repeat no bars are given. A cross-over design isused for all three tests.

Blood glucose levels remain reasonably constant after consumption of thecommercial bar and the bars of Type 1. Blood glucose levels dropseverely after commencing exercise in the test where no bars areconsumed. Further results are listed in table 1.

Bar Type 1 Commercial Bars No Bars Mean completion 3093 3177 3171time(s) Mean Speed 20.48 19.92 19.95 (km/h) Mean Energy Cost 3232 34333389 (10⁻⁴)

The mean energy cost is calculated by multiplying the time to complete 8circuits by the number of heartbeats.

The bars of Type 1 result in much improved performance and a lowerenergy cost. None of the skiers suffered from acid reflux symptoms afterconsumption of the bars of Type 1.

What is claimed is:
 1. A method of maintaining raised blood glucoselevels in a mammal during exercise and/or preventing or delaying theonset of hypoglycemia during exercise in a mammal, the method comprisingorally administering to the mammal a nutrient composition containingcarbohydrate and at least 9% by weight beta-glucan.
 2. The method ofclaim 1 wherein the nutrient composition contains at most 15% by weightbeta-glucan.
 3. The method of claim 1 wherein the nutrient compositioncontains up to 60% by weight of carbohydrate.
 4. The method of claim 1wherein the nutrient composition contains 45% to 55% by weight ofcarbohydrate.
 5. The method of claim 1 wherein the nutrient compositionfurther comprises 8% to 18% by weight fats.
 6. The method of claim 1wherein the nutrient composition comprises 8% to 18% by weight protein.7. The method of claim 1 wherein the nutrient composition includes afibre rich cereal which provides carbohydrate and the β-glucan; thefibre rich cereal containing at least 14% by weight β-glucan and atleast 30% by weight of total fibre.
 8. The method of claim 7 wherein thefibre rich cereal is in the form of an extrusion cooked cereal.
 9. Amethod of preventing or delaying the onset of hypoglycemia duringexercise in a mammal, the method comprising orally administering to themammal 30 minutes or less before or during the exercise a betaglucanenriched nutrient composition containing carbohydrate wherein the amountof betaglucan is at least 9% by weight of the nutrient composition. 10.The method of claim 9 wherein the nutrient composition contains at most15% by weight beta-glucan.
 11. The method of claim 9 wherein thenutrient composition contains up to 60% by weight of carbohydrate. 12.The method of claim 11 wherein the nutrient composition contains 45% to55% by weight of carbohydrate.
 13. The method of claim 9 wherein thenutrient composition further comprises 8% to 18% by weight fats.
 14. Themethod of claim 9 wherein the nutrient composition comprises 8% to 18%by weight protein.
 15. The method of claim 9 wherein the nutrientcomposition includes a fiber rich cereal which provides carbohydrate andthe betaglucan; the fiber rich cereal containing at least 14% by weightbetaglucan and at least 30% by weight of total fiber.
 16. The method ofclaim 15 wherein the fiber rich cereal is in the form of an extrusioncooked cereal.
 17. A method of improving performance during an exercise,the method comprising orally administering to a mammal during theexercise a beta-glucan enriched nutrient composition containingcarbohydrate wherein the amount of beta-glucan is at least 9% by weightof the nutrient composition.
 18. The method of claim 17 wherein thenutrient composition contains at most 15% by weight beta-glucan.
 19. Themethod of claim 17 wherein the nutrient composition contains up to 60%by weight of carbohydrate.
 20. The method of claim 19 wherein thenutrient composition contains 45% to 55% by weight of carbohydrate. 21.The method of claim 17 wherein the nutrient composition furthercomprises 8% to 18% by weight fats.
 22. The method of claim 17 whereinthe nutrient composition comprises 8% to 18% by weight protein.
 23. Themethod of claim 17 wherein the nutrient composition includes a fiberrich cereal which provides carbohydrate and the beta-glucan; the fiberrich cereal containing at least 14% by weight beta-glucan and at least30% by weight of total fiber.